Rapid developments of computers have made the information industries of today so prosperous. Studies on methods to output a great amount of recorded information have been enthusiastically made. In this technical field, a reversal silver halide photographic material has been used as the recording material. In the reversal image forming process, a negative image is formed by a first development; the negative image is bleached without fixing to remove a reduced silver from the negative image (desilvering); the remaining undeveloped silver halide is exposed to light; and a second development is carried out to form a positive image. The steps of the process are so complicated that a finishing speed of the film is slow and a maximum density (Dmax) and a minimum density (Dmin) are not stable. Further, a strong oxidizing agent such as potassium dichromate must be used in a bleaching bath.
A direct positive image forming process has been proposed to solve the problems of the reversal image forming process. In this process, a direct positive image can be obtained without using a negative film.
The known direct positive silver halide photographic materials can be classified into two types exclusive of special cases which are not practically used.
One is a process using a fogged silver halide emulsion. A direct positive image is by a developing process after the fogged nuclei (latent image) is destroyed within the exposed area by solarization or Herschel effect.
The other is a process using a non-pre-fogged internal latent image type silver halide emulsion. A direct positive image is obtained by carrying out an imagewise exposure and then conducting a surface developing process after or simultaneously with a fogging treatment.
A process of using a nucleating agent, called "chemical fogging process" has been known to produce selectively a fogged nucleus as is described above. The fogging process is described in "Research Disclosure", Vol. 151, No. 15,162, p. 72-87 (Nov. 1976).
The internal latent image type silver halide emulsion means such a silver halide emulsion that sensitivity specks exist mainly inside the silver halide grains and a latent image is formed mainly inside the grains by exposure.
The process of the latter type generally has a higher sensitivity as compared with the process of the former type. Therefore, the internal latent image type is suitable for use application in which a high sensitivity is required.
Various internal latent image type emulsions have been proposed in this technical field. For example, the emulsions are described in U.S. Pat. No. 2,592,250, No. 2,466,957, No. 2,497,875, No. 2,588,982, No. 3,317,322, No. 3,761,266, No. 3,761,276 and No. 3,796,577, and U.K. Patents No. 1,011,062, No. 1,151,363 and No. 1,150,553. The photographic material described in these documents has a relatively high sensitivity for the direct positive type.
The direct positive image forming system is described in detail in T.H. James, "The Theory of the Photographic Process" 4th ed., Chap. 7, pp. 182-193 and U.S. Pat. No. 3,761,276.
The developing solution of the non-pre-fogged internal latent image type silver halide light-sensitive material usually is a high alkaline solution of hydroquinone-metol or hydroquinone pyrazolidone having a pH value of not less than 10.5.
An amino compound has been contained in the developing solution to accelerate the development. Japanese Patent Provisional Publication No. 56(1981) - 106244 discloses an amino compound such as N-methylaminoethanol.
N-methylaminoethanol is relatively inexpensive and easily available, and shows excellent developing effect. However, it has various problems as is described below.
1. Amines usually have offensive odor like fish. The odor is unfavorable in various stages such as preparation of a developing solution, introduction of the solution and treatment of the solution.
2. Lower alkyl amines (e.g., N-methylaminoethanol) have a low boiling point. They often produce smoke when the solution is handled. The smoke adheres to the surrounding machines and walls to make those machines and walls sticky.
3. Amines have a high absorption capacity of CO.sub.2 existing in the atmosphere, so that the amines absorb CO.sub.2 from the atmosphere having a large amount of CO.sub.2, whereby pH of the developer is lowered. Therefore, the developing activity is decreased.
4. It is known that amines often deteriorate plastic parts of an automatic developing machine which is used for the photographic process.
5. For the effective developing acceleration, a large amount such as an amount of 40 to 80 g per 1 liter of the developing solution is needed, so that the cost becomes high and the concentration of the developer is difficult.
6. Amines are liquid at normal temperatures Therefore, they cannot be used to prepare the later-described one-pack type powdery processing agent which is advantageously used for saving the space of containers.